Wear Resistance of Certain Nuclear Reactor Components Made of Zircaloy-2 $( \mu m )$

Wear resistance of certain nuclear reactor components made of Zircaloy-2 is partly determined by properties of the oxide layer. The following data appears in a study that proposed a new nondestructive testing method to monitor thickness of the layer. The variables are x =oxide-layer thickness ( $( \mu m )$ and y =eddy-current respond (arbitrary units). $\begin{array} { c c c c c c c c c c c } \hline x & 0 & 7 & 17 & 114 & 133 & 142 & 190 & 218 & 237 & 285 \\\hline x & 20.3 & 19.8 & 19.5 & 15.9 & 15.1 & 14.7 & 11.9 & 11.5 & 8.3 & 6.6 \\\hline\end{array}$ The equation of the least squares line is $\hat { y }$ =20.6 - .047x. Calculate and plot the residuals against x and then comment on the appropriateness of the simple linear regression model.